Why place all the dV requirements for ascent/descent on the lander, and in doing so drive up the requirements on the lander significantly when an upper stage can do the work here? A Xeus-Centaur is at least partly off the shelf, IVF is scheduled to be demo'd in 2018. Investment in that area would have a much greater return IMO then trying to make a capsule perform a 2-way trip.

Xeus-ACES might be 5+ off, but Xeus-Centaur could be much sooner.

Nope. Masten is tied up with XS-1. ULA is at a point they can't afford any distractions.

That's what I was getting at.

And why I didn't remark about your earlier comment was that it was too desperate to be believed.

It's not about being worthy, it's about having enough operational experience to bring this off. Masten doesn't.

There are four US in active use on the globe that can be made to have on orbit lifetimes of weeks. Could be modified for the thermal environment. Can't take this further.

One of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.

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Gets the Lunar Dragon concept at least to the point where with moderate increases in ISP (canted, partially expanded nozzles) and a large increase in prop meet the ascent requirements.

Yes.

They are most of the way there already if you simply trim the Dragon's mass budget - remember that the LM needed a 5 year diet to make it to Apollo 11 - even Apollo 10's LM was too heavy!

BO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.

Nope. Masten is tied up with XS-1. ULA is at a point they can't afford any distractions.

That's what I was getting at.

And why I didn't remark about your earlier comment was that it was too desperate to be believed.

It's not about being worthy, it's about having enough operational experience to bring this off. Masten doesn't.

There are four US in active use on the globe that can be made to have on orbit lifetimes of weeks. Could be modified for the thermal environment. Can't take this further.

My comment was hand-waving for sure. However even with $2B as you proposed on page 1 to one of the commercial crew providers there are still going to be significant schedule and personnel allocation challenges. They all have full plates, so why draw the line at a crash program to modify an LEO capsule to a lunar lander vs a crash program to modify an US to a crasher stage?Masten is probably too small I agree, however ULA is downsizing so one could argue that they have ALL the necessary resources other than funding.

BO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.

Blue Origin didn't have a lot visible for a suborbital rocket and capsule, then one day it was flying.

Do you have any insider information on the progress of their biconic capsule?

I've tried researching that on the NASA CRS contracts and came up pretty empty, but that's typical for their level of secrecy. I know they want to use a composite PV that has had assistance but most other support went to New Shep.It isn't realistic to think that they have a complete crew vehicle all ready to go, however without knowing exact progress to date I don't think its fair for outright dismissal of something emerging in a 2-4 year time frame.

One of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.

BO's plate is full for the next five years. Note also the game has gone up with the recycling of fairings. There's a few more things to come. And he doesn't have a orbital crew capsule yet. Or a orbital capsule recovery system with precision landing.

Blue Origin didn't have a lot visible for a suborbital rocket and capsule, then one day it was flying.

Do you have any insider information on the progress of their biconic capsule?

Suggest that you notice how much of there agenda "moves along", in public.

For them to advance to a NS business, they've already said they need to launch weekly. They haven't been launching weekly.

For them to advance to orbital capsule, they need to finish/operate a NS capsule, to then "move on" to orbital capsule.

Note, that all NG provider business they've talked about is big geosats. They've only shown fairings on NG so far.

And the lunar reference is cargo only. All of this is consistent.

Suggest BO is attempting to play "catch up" with Musk on the reusable LV side (makes sense because he doesn't want Musk to dominate that market), and that HSF follows after that 2-3 year program.

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I've tried researching that on the NASA CRS contracts and came up pretty empty, but that's typical for their level of secrecy. I know they want to use a composite PV that has had assistance but most other support went to New Shep.It isn't realistic to think that they have a complete crew vehicle all ready to go, however without knowing exact progress to date I don't think its fair for outright dismissal of something emerging in a 2-4 year time frame.

You can't hide an orbital HSF program. Trust me, the AF tried that and failed, with 25x Bezos resources.

He's not hiding an unmanned orbital program. You can look closely for the HSF parts and they are not there. Likely they will play catch up on the HSF part afterward.

One of the simpler ways of dealing with this could be creative use of PAM's, but it is so ridiculous one hesitates to bring it up. No contingencies at all too. Hinted at it earlier because they are still flight qualified for F9/FH.

Ah yes, coming around full circle to earlier posts where I suggested Delta II US and Antares US (Castors)...The required propellant mass needs to be at least 5000kg for ascent vehicle alone even using Dragon 2's engines for partial dV. Some of the larger ATK motors may do it. So the D2 can be used for initial lift off and final burn to orbit where the solid kick motor provides the majority of dV.

More of a cludge, but makes for less "upgrading" of each component. Keeping with pressure fed smallish canted nozzles for Dragon2 and existing or slightly enlarged tanks.

I know I'm necroing a bit here, because this thread hasn't been active in ten months, but I've played around with this idea in the past and so this thread was quite interesting to me.

Falcon Heavy expendable is advertised at 63.8 tonnes to LEO, 26.7 tonnes to GTO (LEO+2.27 km/s), 16.8 tonnes to trans-Martian injection (LEO+4.3 km/s), or 3.5 tonnes to trans-Plutonian injection (LEO+8.2 km/s). For each case, the total dV provided by the upper stage can be calculated trivially using the rocket equation, using the stage dry mass of 4 tonnes, the propellant load of 107.5 tonnes, and the isp of 345 seconds.

As the payload mass decreases, the total amount of dV in the stage increases, as does the remaining dV in the stage after orbital insertion. Plotting leftover dV against total dV for a range of payloads produces a closely linear plot:

The equation for the linear trendline is y=0.72x + 3.25, by the way.

This allows us to estimate the total stage dV in the stage for any given BLEO destination, which in turn can be used to estimate the payload for that destination. TLI is 2.73 km/s beyond LEO, which gives us a total stage dV of 5.22 km/s. By the rocket equation, this means a propellant fraction of 78.67%, or a payload of 25.15 tonnes.

Of course, there are a few other options. What if the Falcon upper stage was modified to allow for extended restarts, as has been proposed a few times on this thread? It could, in theory, provide both the TLI burn AND the LOI burn, a total cost of 4.04 km/s. Our model predicts a total stage dV of 6.17 km/s, a propellant fraction of 83.88%, and a payload of 16.66 tonnes.

And, finally...perhaps the most ambitious idea of all: what if you used an even smaller payload and then used the Falcon Heavy upper stage as a crasher to drop a Dragon 2 right above the surface, where it could use its thrusters to hover and land? Well, that's 5.93 km/s beyond LEO, a total predicted stage dV of 7.54 km/s, a prop fraction of 89.23%, and a payload of 8.98 tonnes.

Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

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Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

The upper stage on today's Falcon Heavy has modifications to allow extended restart, though likely not in the week-or-more range. Doesn't mean it would be impossible, though.

If SpaceX didn't want to expend a whole Falcon Heavy, they could send up the lunar module on a Falcon 9 followed by a reusable Falcon Heavies with one simply having an IDA mated to the PAF, as proposed upthread. They would dock, and then the Falcon Heavy upper stage could then perform the TLI and LOI, which also means you don't need to man-rate the Falcon Heavy.

Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

Another solution just include third stage using storable propellants which would remove the need for a lot of the design changes on the FH second stage.

Having seen extended restart capability with FH, we can say an expendable Falcon Heavy should be able to deliver up to 15.2 tonnes direct to GEO.

I get more like 12-13 tons direct to GSO.

« Last Edit: 02/09/2018 02:45 PM by Robotbeat »

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Great work! That 16.7 t to LEO is pretty useful. The Apollo LM was 15 t, so one FH could deploy an LM into LLO, followed by a propulsive Lunar Dragon (LD) into LLO from another FH. LD would then rendezvous with the LM. The mission profile would then follow Apollo. A 9 t lunar habitat would be pretty useful for a two week mission on the surface. SpaceX just needs to extend the kerolox second stage to 3 to 4 days. This was planned for the Soviet N-1/L-3 missions, but never implemented.

Another solution just include third stage using storable propellants which would remove the need for a lot of the design changes on the FH second stage.

Yes, that's one solution. But storables aren't going to get quite as much isp as the MVac, even factoring in boil-off. And while it's not quite as mass-efficient on the way there, since you're bringing along extra tankage, it means lower mass in LLO and thus both a lighter and more compact lunar spacecraft.